/* px em rem 等长度单位演示 */
html{
    font-size: 62.5%;/*16px*0.625=10px*/
}

body{
    font-size: 1.2em;
}

.value_px{
    font-size: 32px;
}

.value_em{
    font-size: 2em;
}

.value_rem{
    font-size: 2rem;
}

/* 颜色值 */
.color_name{
    color:red;
}

.color_hex{
    color: #00ff00;
}

.color_fun{
    color:rgb(0, 0, 255)
}

/* 图片函数url */
.img_url{
    width: 260px;
    height: 70px;
    background-image: url("qq_logo.png");
    font-weight: bold;
}

/* 常见字体样式属性 */
.font_demo{
    /* font:400; */
    font-family:微软雅黑, sans-serif;
    font-size: 2em;
    font-style: italic;
    font-weight: normal;
}

/* 常见文本样式属性演示 */
.text_demo{
    font-size: 2em;
    border: 1px solid black;
    width: 50rem;
    height: 10rem;
    text-align: left;
    line-height: 10rem;
    text-decoration: underline;/*添加下划线，删除线等等*/
    text-indent: 3rem;/*缩进*/
    letter-spacing: 1rem;/*给字体增加间距*/
    word-spacing: 2rem;
}

/* 列表样式属性 */
ul{
    font-size: 2rem;
}
.list_demo1{
    list-style: circle inside;
}

.list_demo2{
    list-style: none;
}
.list_demo3{
    list-style-image: url(qq_logo.png);
    list-style-type: none;
    list-style-position: inside;
}
.list_demo4{
    list-style: none url(la.png) inside;
}

/* 背景样式属性 */
.bg_box{
    border: 1px solid red;
    width: 40rem;
    height: 10rem;
}
.bg_demo1{

    background-color:coral;
}

.bg_demo2{
    background-image: url(qq_logo.png);
}

.bg_demo3{
    background-image: url(qq_logo.png);
    /* background-repeat: no-repeat;检查图片是否重复 */
    background-repeat:repeat-y;
}

.bg_demo4{
    background-image: url(qq_logo.png);
    background-repeat: no-repeat;
    background-position: center center;/*（距离左端位置/left/right/center/```，距离顶端位置/bottom/center/```）单位px*/
}

.bg_demo5{
    background-image: url(qq_logo.png);
    background-repeat: no-repeat;
    background-position: top right;
    background-attachment: fixed;
}

.bg_demo6{
    background: #c2f3c2 url(qq_logo.png) repeat-x top  right fixed;
}

/* 表格样式 */
.table_demo{
    font-size: 2rem;
    border: 1px solid black;
    width: 70%;
    margin: 0 auto;
    caption-side: top;
    table-layout: fixed;/*使文字等分*/
    border-collapse: collapse;
    /*边框细线间距 separate双重边框通常使用collapse折叠到一起*/
    /* border-collapse: separate; */
    border-spacing: 10px;/*需要间距就要用separate*/
    empty-cells: show;

}

.table_demo caption{
    font-size: 2.5rem;
}

.table_demo th, .table_demo td{
    border-top: 1px solid black;
    border-bottom: 1px solid black;
    text-align: center;
}

.table_demo thead{
    background-color: rgb(187,39,39);
    color:white;
}

.table_demo tbody tr:hover{
    background: #d8e61d;/*鼠标移动上去产生的效果*/
    cursor: pointer;/*鼠标覆盖上去的形状*/
}

.table_demo tfoot td{
    text-align: right;/*文本位置*/
    padding-right: 20px;
}

/* 表单样式 */
.form_demo{
    font-size: 1.4rem;
    border: 1px solid seagreen;
    background: #fff;
    width: 35rem;
    height: 25rem;
    text-align: center;

}

.form_demo input[type="text"],.form_demo input[type="password"]{
    border-left: 0;
    border-right: 0;
    border-top: 0;
    border-bottom: 1px solid #000;
    width: 200px;
    height: 39px;
    padding-left: 44px;
    
}

.form_demo #username{
    background: #fff url(username.png) no-repeat top left ;

    
}

.form_demo #pwd{
     background:#fff url(password.png ) no-repeat top left;
}

.form_demo [type="submit"]{
    width: 100px;
    height: 38px;
    background-color: rgb(233, 85, 85);
    border: 1px dashed #2e5bec;
    border-radius: 10px;
    color: aliceblue;
    text-align: center;
}